Method of charging blast furnaces



Dec. 29, 1942. T. H. K ENNEDY METHOD OF CHARGING BLAST FURNACES FiledAug. 4, 1941 liweizfaiw 7l/MZ4/V A K /y; K .@i 5- large fiues.

Patented Dec. 29, 1942' METHOD OF CHARGING BLAST FURNACES S TrumanKennedy, McKeesport, Pa., assignor to National Tube New Jersey Company,a corporation of Application August 4, 1941, Serial No. 405,398

1 Claim. (cram-152) This invention relates to blast furnaces, and moreparticularly to the method of admitting and distributing the charge tothe furnace.

Most commercial blast furnaces comprise a hopper, from wh ch they areadmitted to the.

furnace in a regulated or controlled manner.

Usually the hopper comprises a unitary structure of an upper truncatedcone from which there depends a lower inverted truncated cone. top ofthe upper truncated cone has a central opening with wh ch there communcates a feeding 'cylinder. there extends a shaft carrying on its lowerend a large bell valve which closes a central opening in the lowerinverted truncated cone, together with a smaller bell valve which closesthe lower end ofthe feeding cylinder. The upper small bell valve opens anumber of times while the large bell is closed, to admit each skip loadof material. After the hopper has been filled with the desired charge,the small bell valve is maintained in such position as to close thelower end of the feeding cylinder, and the large bell valve is opened topermit the received charge to flow through the central opening in thelower inverted truncated cone. Frequently the'small bell valve isrotated to provide better distribution.

In the operation of the furnace, hot air under pressure is forced intothe lower part of the furn-ace from a large supply line through a seriesof tuyeres. ,This hot air rises through the massof ore, coke, andlimestone, to the top of the furnace, and in its ascent the chemicalconstituents of the air combine with those of the ore, coke andlimestone and the'products of combustion (exhaust gases) areconductedaway by means of Due to the combustion of the coke, and the variousreactions occurring in the body of the ore mass and the-periodic tappingof the molteniron, the whole body of material gradually sinks .and thereis a constant downward movement of the entire contents of .the furnace.Subsequently new material is admitted to the stock line of the formationby the action of the bell and hopper described hereinbefore, and thecycle of"'operatfi n goes on continuously. As the furnace gases risethrough the furnace charge, they The" pass more readily than otherregions wherein they are retarded. The vertical center of the chargepermits the gases to pass more readily than does the zone between thevertical center and the outer periphery. This last-namedzone (i.e.,between the vertical center of the charge and the periphery) which ismore or less impervious to the flow of the gases, may fail to provideits. share of the flow passage, with the result that there is formed averticalannular ring or column of material upon which there has beenlittle gas action until approaching close to the bosh portion of thefurnace which, as aforesaid, is adjacent the crucible at the bottomthereof.

Ordinarily, blast furnaces are constructed in the form of an elongatedhollow truncated cone,

Through this feeding cylinder to permit the mass to spread out as itdescends, whereby the rising gases flow more freely than i wouldotherwise be thecase. However, this con- .struction is not sufficient toeliminate the difficulties described hereinbefore.

Among blast furnace operators, it is commonly considered good practiceto avoid the formation at any point-in the ore-fuel mass from thevertical center line-to the inner walls of the furnace,. any region sodense, as to be impervious to, or

block the flow of, the upwardly moving gases. That is to say, thematerials should be deposited inthe furnace in such manner, sequence,and quantity that the result is a more even distribution of materialsover the entire area of the stockline; fine materials should not beaccumulated apart from the coarse materials, and the coarse materialsshould not be segregated apart from the-fine materials.

It is, of course, true that there are numerous variables in the qualityand composition of ores, fu ls and limestone; but the relative diametersof hopper. bell and furnace wall, the slope of the bell surface, and theextension of the edge of the bell beyond the hopper and depth of thestock encounter zones or channels through which they line, aresubstantially constant.

As the large bell valve is lowered, the material falls to the sto ckline, and builds up an" annular ring of material, forming a peak whichis sometimes at a distance from the wall of thefurnace.

This annular peaked ring is therefore a circular ridge running aroundthe stock line of the furnace. On the inner slope (i. e., that which istoward the center of the furnace) the gradient of theridge is uniform,and conforms to the angle of repose of the material, while on the outerslope there may be a shallow pocket formed at the top which ray or maynot entirely fill up with m s- 2 cellaneous materials. This shallowpocket is the result of prevention of the orderly formation of a slopedue to the adjacency of the annular wall of the furnace.

It is among the objects of the present invention to provide va method ofoperating a blast furnace bell valve which will collectively result inthe very even distribution of the charg within the blast furnace. Morespecifically, the invention seeks to so control the tendency of thefallingj material to form a peak that the ordinary circular ridgecondition will be broken up, and in lieu thereof the pattern of materialwill have a sinuous or serpentine path or direction. This sinuous orserpentine path of direction is in contact with, or tangent with,thewalls of the furnace at one point, and immediately leaves the wallregion to traverse a region at any fixed and suitable distance away fromthe wall, returning again to the wall at regular intervals of spaceuntil the entire periphery of the outer rim of the stock bed has beenzigzagged over and over. By the same device, two sinuous curves of ridgeformation are established, one curve overlapping the other to the extentthat the crests of one curve cover the troughs of the second, and thetroughs of the first overlap the crests of the second.

To the accomplishment of this and other desirable objects and purposes,I have designed the present, preferred embodiments of the inventionpresented in the accompanying drawing forming a part of thisspecification and to which refer ence should be had in connection withthe following detailed description, and in this drawing, for simplicity,like reference numerals have been employed to designate the same partsthroughout the several views.

In said drawing, Figure 1- is a fragmentary cross-sectional elevation ofthe upper end of a blast furnacewith its feeding cylinder, hopper, smallbell valve, etc., all of which are of conventional design; andillustrating in connection therewith the large bell valve of the presentinvention, which is shown in elevation.

Figure 2 is a horizontal sectional view of the stack of the blastfurnace, with the large bell valve of Figure 1 shown in plan, togetherwith a diagrammatic illustration of the manner in which the large bellvalve is operated in accordance which the principles of the presentinvention are employed.

Referring more particularly to the drawing, the numeral I designates thetop of the stack of a blast furnace of conventional design,'the saidstack being cylindrical in shape and composed of refractory brickwork.

Superposed on the stack I is a frusto-conicaltop 2 which supports thehopper of the blast furnace. This hopper comprises an upperfrusto-conical portion 3 and a lower inverted -fru'sto-conical portion4. The upper portion 3 of the hopper-is provided with a central aperturethrough which there extends a feeding cylinder 6. Through the feedingcylinder 6 and into the hopper composed of the upper and lower portions3 and krespectively, there extends a shaft I carrying at its lower endthe large "bell valve 9 of the present invention. Within the feedingcylinder 6 the shaft I carries a slidable sleeve I9, between the lowerend of which and the large bellvalve 9 is a small bell valve II which isadapted to seat against, and close, the lower end of the feedingcylinder 6.

In practice, the small bell valve I I on the lower end of the slidablesleeve I0 is opened a number of .times, while the large bell valve 9 onthe lower end of the shaft 1 is maintained in closed position. After thehopper composed of the upper and lower portions 3 and A respectively,has been filled with the desired charge, the small bell valve-I I ismaintained in closed position in order to close the lower end of thefeeding cylinder 8, and the large bell .valve 9is opened to permit thereceived charge to flow through the central aperture in the lowerportion of the hopper. In addition, rotation is imparted to the shaft Iwhen in its lowered position, in order to more evenly distribute thematerials to be charged to the blast furnace. The foregoing operationand the mechanism for accomplishing the same are believed to be so wellknown to those skilled in the art as not to require illustration herein.

The major portion of the large bell valve 9 has the conventional smoothconical surface, but, according to the teachings of the presentinvention, it carries an extended skirt portion I2 the edge or margin ofwhich is provided with skill?" ous or serpentine serrations, theinwardly bellied portions of which are designated at I3 and theoutwardly bellied portions at I4. As a specific embodiment, the extendedskirt portion I2 of the large bell valve 9 may have six inwardly belliedportions I3 and. six intermediate outwardly bellied portions I4. Such anarrangement will space the inwardly bellied portions I3 and outwardlybellied portions ll at SO-degree intervals. The extended length of theskirt portionl2 of the large bell 9 may be varied to give the desiredspread of peak ridges of fine material.

As the large bell 9 is lowered to the dotted line position, the materialescapes from the hopper composed of upper and lower portions 3 and 4respectively, and the extended skirt I2 on the margin of the large bellvalve 9 determines the posi-- tion on the stock line on which thematerial will fall. Two factors determine the location of this position,one being the depth of the inwardly bellied portions I3 and outwardlybellied portions I4, and the other being the length of the extendedskirt I2. The serpentine path of the peak ridge on the stock line makesa curve with deeper serrations than the corresponding ones on the marginof the large bell valve 9. This is due to the fact that the particles ofmaterial released from the hopper gain a certain momentum as they rolldown this extension.

. The longer the extended skirt I2 extends beyond the hopper at theoutwardly bellied portions M, the greater distance the particles willtravel from the large bell valve 9 toward the walls of the furnace, andthe shorter the extended skirt I! at the inwardly bellied portions I3,the less the momentum of the particles and the shorter distance theywill travel from the bell valve, or the farther they will be from thevertical walls of the furnace. Therefore two factors enter into thelocation of pattern of peak ridge: first, the distance of the points [3and I4 from the wall I and stock line of the furnace; and the distanceon the extended skirt l2 from the inwardly bellied portions l3 andoutwardly bellied portions M to the discharge aperture of the hopper.

Referring to Figure 2, the concavo-convex line 23-24 illustrates thepath of the peak ridge of fine material upon the stock line when thelarge bell valve 9 is lowered vertically from the closed position. Thecrest or convex portions 24 of the concavo-convex line 23-44 are indirect contact with the circular interior wall of the blast furnace, asrepresented by the numeral l and the concave portions 23 of theconcavo-convex line 23-24 are located at any desired distance therefrom.The extreme positions of the con cavo-convex line '23i-24 are connectedby a smooth sinuous curve.

In the event that the large bell valve 9 embodies six inwardly belliedportions l3 and six intermediate outwardly bellied portions M, as in theembodiment described hereinbefore, as the said large bell valve 9 israised it is rotated approximately 30 degrees, or about one-half of aserration. The raising and lowering of the large bell valve 9 and themanner of its rotation is,

as before stated, accomplished in a manner which is believed so wellknown to those skilled in the art as not to require illustration herein.

lifter the large bell valve 9 has been raised and rotated approximately30 degrees, the hopper comprising the upper and lower portions 3 and 4respectively, filled, and the large bell valve 9 again lowered to theposition designated in Fig- 1 ure 1, the material will be dischargedfrom the stock line in the same manner as that described hereinbefore,except that due to the 30-degree rotation the pattern of the peak ridgewill take the form illustrated in dottedlines in Figure 2. This resultsin the supplanting of what was formerly a dense annular zone or pipe offine materials, with a much broader zone, wherein the fine materials arewell distributed throughout the coarse materials. Similarly, every zonefrom the outer rim to the vertical center is affected by this method ofdistribution and improved by a more eve distribution of materials andsizes over the entre area of the stock line.

With the approximately 30-degree 'rotation' described hereinbefore, theconcavo-convex curves 23- 24 cross each other at nodal points designatedat X. Constant repetition of these deposits may cause dense masses toaccumulate at these nodal points X. However, a breakingportions 34 onthe interior of the lower inverted frusto-ccnical portion 4 of thehopper. These inwardly bellied portions 33 and-outwardly belliedportions 34 may be formed as a component part of the hopper structure,as shown, or may take the form of a detachable insert. When using thismodification, the large bell valve 39 takes an entirely smooth conicalform in a manner well known to the prior art.

. When using the modification of Figures 3 and 4, as the conventionallyformed large bell valve 39 is lowered and material allowed to escape outover the margin thereof, the particles composing the material imprisonedwithin the hopper will attain varying momentum as they roll down theoblique surface of the bell overhang. The momentum of the particles willvary from point-to point around the margin of the bell valve. Materialreleased at point 40 will have less momentum than that released at point4|. Material will, therefore, leave the conventional large bell valvewith varying velocities and will land at unequal distances from itsmargin upon the stock line. Therefore there will have been formed, as inthe embodiment first described,a deposit of material upon the stock linehaving a sinuous or serpentine direction reproducing in enlarged formthe pattern of the serrated inner conformation of the hopper. the largebell valve need not be rotated. -Instead there may be employed means forrotating that portion of the hopper which has the sinuous curved innersurface, moving it an angular distance of one-half of one serration, orone-half of one serration plus or minus a given amount, in the manner ofthe preferred embodiment.

It is to be noted that in the device'of the preferred embodiment theentire margin of the large bell valve 39, or the points at which therolling or sliding material leaves the same, are at fixed and equaldistances from the furnace wall I and, therefore, the advantages of thisform of the invention rest solely upon the conception of a variableoverhang as measured from any point on the serrations in the hopper tothe margin of the largebell valve.

While we have shown and described several specific embodiments of theinvention, it will be understood that we do not wish to be limitedexactly thereto, since variousfurth'er modifications may be made withoutdeparting from the scope of the invention as defined by the followingclaim.

I claim:

The method of charging material in a metalfore but with the sinuousridge formed thereby intersecting at spaced points the sinuous ridge ofthe material previously charged.

TRUMAN H. KENNEDY.

In this proposal,

